The present invention relates to molecular imprinting polymers, and, at least in some embodiments, to novel calcium alginate polymer microcapsules and films, and their associated methods of use.
A molecular imprinting polymer (“MIP”) is generally a crosslinked polymeric network formed in the presence of an imprinting compound or “template molecule” such that the template molecule may be later removed, leaving a MIP that is able to recognize and bind to the template molecule via a complementary binding cavity. The release of the template molecule allows the MIP material to exhibit a selective “memory” with respect to the template molecule. This simulates the typical molecular recognition of biological systems, such as antibodies or enzymes. MIPs tend to show a certain chemical affinity for the original template molecule and, consequently, can be used to fabricate sensors, as catalysis, or for separation methods.
Molecular imprinting has been successfully used to recognize small molecules, such as herbicides, metal ions, and amino acids. Thus, MIPs can be used as sensors, chromatography beds, resins for separation processes, and analytical tools in enzyme-linked immunosorbent assays (“ELISA assays”).
Heretofore, bio-macromolecules, such as antibodies and enzymes, have been employed for protein recognition purposes. However, such bio-macromolecules are sometimes difficult to find and/or produce. Thus, there is a need for receptor-like synthetic materials such as protein-imprinted polymers as substitutes for natural receptors.
However, the development of MIPs capable of recognizing macromolecules, such as peptides and proteins, has met with many difficulties. The current approach to macromolecular imprinting generally involves the inclusion of a template molecule within a polymer formed from functional monomers and crosslinking agents. However, macromolecular imprinting technologies heretofore have been generally incompatible with the diagnosis and recognition in many life sciences applications, such as medical applications, food additives, or drug delivery, which require biocompatible or alimentary products.
Alginate is generally a water soluble linear polysaccharide derived from brown algae and composed of alternating blocks of 1,4′ linked α-L-guluronic and β-D-mannuronic acid residues (FIG. 9). Physical networks are formed by the exchange of sodium ions associated with the guluronic acid residues with divalent cations in the cross-linking solutions. The guluronic residues stack to form a characteristic egg-box structure. Dimerization of the alginate chains occurs through the divalent cations, as illustrated in FIG. 10, causing junctions between many chains to create a network structure. Although the biocompatibility and biodegradability of alginates has been documented, only limited studies have been done using alginate microcapsules to achieve macromolecular imprinting. In fact, it is believed that each of the works to date have used the inverse suspension method to produce alginate microcapsules, which involves the use of organic chemicals, such us chloroform and hexane, that are incompatible with the medical and alimentary purposes. Similarly, such attempts have been able to achieve at most a recognition of between about 0.46 mg to about 0.66 mg of the template molecule bovine serum albumin (“BSA”) per gram of microcapsule. In addition, in these works, typically at least 48 hours has been required to achieve the release of the template molecule.